It’s hard to imagine just how little freshwater exists on Earth compared to saltwater. If you’re teaching the water cycle, your students might be amazed to learn that less than 3% of the Earth’s water is freshwater—the rest is saltwater. In this post, I’ll show you a hands-on freshwater learning activity that uses simple kitchen measurements to help your students visualize these proportions. This activity is a powerful way to help students truly understand how rare freshwater is!
Before we dive in: If you’re an educator planning to teach the water cycle, great learning resources are key to deepening understanding! I think you and your students will love my complete Water Cycle Unit (plus you’ll support my blog with your purchase! ❤️)
Background Information
Most of the water on earth is saltwater (~97.5%), like the water in our oceans. Also, a significant amount of earth’s water is frozen such as in glaciers and ice sheets (~1.7%). Fresh groundwater makes up ~0.75% of the water on Earth, and fresh surface water such as the water in streams and lakes is about ~0.01% of the water on Earth. Additionally, about ~0.001% of earth’s water is in its gas form as water vapor in our atmosphere. Having trouble visualizing this? This activity can help you visualize the relative amounts of freshwater on Earth!
Materials
Gather the following materials. You can complete this entire lab with common kitchen measuring cups.
- ~1 gallon of water
- Large 1+ gallon bucket or container
- Liquid measuring cup
- Tablespoon
- 8 ice cubes
- Teaspoon
- Eye dropper
- Extra containers to hold water
Step-by-Step Directions
Work through the following steps with your students. Explain what each measurement represents as you work through the activity.
- Measure 1 gallon (16 cups) of water into the bucket. This represents all the water on earth.
- From the water in the bucket, remove ¼ cup of water and set aside. Replace it with 8 ice cubes. These represent the earth’s frozen water such as glaciers and ice sheets.
- From the water in the bucket, measure 2 tablespoons into an extra container. This represents the Earth’s fresh groundwater.
- From the water in the bucket, use an eyedropper to measure 8 drops of water into an extra container. This represents all the surface water on earth, such as streams and lakes.
- From the water in the bucket, use an eyedropper to measure 1 drop of water into an extra container. The amount of water vapor in our atmosphere at any time is represented by slightly less than this amount!
- Look at the water remaining in the bucket. This represents the saltwater on earth, mostly water in our oceans but also including salty groundwater near coasts and saltwater lakes, ponds, and marshes.
Free Printable Directions for This Activity
A printable version of these directions can be found on my free resources page. As my email subscriber, you’ll gain access to the free resources page and get updates about new activity ideas, project guides, new freebies and units, and cool science topics to teach in your classroom! Subscribe now to access the freebies page and more!
What’s Next?
If you’re teaching the water cycle, I think you’ll love some of my other blog posts too. Read my posts about explaining the water cycle in 10 stages and human impacts on the water cycle. You can also learn how to measure different water cycle processes including evaporation, precipitation, infiltration, and stream flow!
Explore more lessons from Wild Earth Lab:
If you enjoyed this freshwater learning activity, I know you will love trying my printable science and nature units in your classroom too!
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